Drive for boom mounted hoist cable



Feb. 1o, 1970 G, WOOLMAN 3,494,594

DRIVE FOR BOOM MOUNTED HOIST CABLE Filed Jan. I5, 1968 United States Patent O 3,494,594 DRIVE FOR BOOM MOUNTED HOIST CABLE Granville Woolman, Naperville, Ill., assignor to Baldwin-Lima-Hamilton Corporation Filed Jan. 3, 1968, Ser. No. 695,440 Int. CI. A62b 1/08; B66c 23/06 U.S. Cl. 254-145 3 Claims ABSTRACT OF THE DISCLOSURE DESCRIPTION OF THE INVENTION This invention relates generally to boom cranes and more particularly concerns a drive for the cable of such cranes.

The primary aim of the invention is to provide a boom cable drive that does not tension or slacken the cable as an incident to swinging the boom up and down. As a result, the danger of inadvertently snapping the cable upon powered tilting of the boom is avoided.

It is also an object of the invention to provide a drive of the above character which is strong, compact and well suited for economical manufacture.

lOther objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE 1 is a side elevation of a crane embodying the invention; and

FIG. 2 is an enlarged fragmentary section taken approximately along the line 2--2 of FIG. l,

While the invention will be described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to that embodiment. On the contrary, I intend to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning to the drawing, there is shown in FIG. l a selfpropelled crane embodying the invention and including a chassis 11 supported on ground wheels 12 and carrying an operators station 13 and a power plant 14. The crane structure itself includes a turntable 15 mounted on the chassis 11 for rotation about a vertical axis, and a telescoping boom 16 mounted on the turntable 15 for tilting movement about a horizontal axis 17. The boom 16 includes a shipper 18 and an extension 19 carrying at its outer end a pulley assembly 21 lwhich guides a cable 22 that supports a hook block 23.

The boom is extended and retracted by an actuator (not shown) within the shipper 18 and its extension 19. The boom is elevated and lowered by a double-acting actuator 24. The cable 22 is payed out and wound in by a motor assembly 26. The turntable 15 includes a base 27, enclosing a motor (not shown) for rotating the turntable, and a pair of spaced generally vertical support plates 28 and 29 mounted on the base 27.

In accordance with the invention, the lower end of the boom 16 is positioned between the plates 28, 29 and provided with stub shafts 31 and 32 journalled in the 3,494,594 Patented Feb. 10, 1970 ICC plates and supporting both a cable drum 33 and the motor assembly 26 which is drivingly coupled to the drum. In the illustrated structure, the plates 28, 29 are of double-walled, box-like construction for strength and rigidity, and the rear or lower end of the boom shipper 18 is formed of plates 34 welded together to form a box-like enclosure 4for the drum 33 on which the cable 22 is wound. The stub shafts 31, 32 are made up of inner and outer annular parts 36 and 37, respectively, bolted to the boom plates 34, The outer stub shaft parts 37 are fitted in sleeve bearings 38 mounted in the support plates 28, 29 so as to define the axis 17 for the boom.

Preferably, the drum 33 is journalled in bearings 41 which are set in the inner ends of the stub shaft parts 36 so that the axis of the lboom 16 and the drum 33 coincide. A cover plate 42 closes lthe outer end of the annular stub shaft 31, and the stub`shaft 32 is formed with a radial flange portion 43 positioned outwardly of the adjacent support plate 29 and carrying the motor assembly 26.

In the preferred embodiment, the motor assembly 26 includes a mounting plate 44 which is fitted in and bolted to the flange portion 43. A bearing 45 is set in the mounting plate 44 substantially concentric with the bearings 41. A drive shaft 46 extends through the drum 33 and is secured by splines 47 at one end to the drum and, at the other end, is journalled by the bearing 45 by being fitted in splined engagement with a motor output member 48 set in the bearing 45. The shaft 46 is held against endwise movement by a snap ring 49 that is locked in position by an end plate 51.

As can be readily seen, vertical swinging movement of the boom 16 also rotates the motor assembly 26 and thus the drum 33 is simultaneously turned. Unless the motor assembly is actuated, the angular relationship between the drum 33 and the boom 16 is not altered as the boom is raised and lowered. Those familiar with this art will appreciate that in cranes in which the cable drum does not rotate with the boom, lifting the hook block to the boom end and then lowering the boom creates a severe safety hazard. The lowering boom wraps more cable about the .fixed drum, and with the hook block being jammed against the boom end, the cable is overloaded and often snapped.

The use of the annular stub shafts 31, 32 provides a convenient and economical way of journalling the boom 16 and the drum 33 on coinciding axes. The mounting plate 44 assures that the output member 48 of the mo tor assembly 2-6 remains properly alined with the other operating elements of the assembly, and the long drive shaft 46 minimizes the effect of any slight misalinement between the drum 33 and the motor assembly 26,

Those skilled in this art will also appreciate that the construction described above is particularly compact and well suited for economical large-scale manufacture.

I claim as my invention:

1. In a crane, the combination comprising, a base, a pair of spaced generally vertical support plates on said base, a boom having its lower end positioned between said plates, said boom having a pair of oppositely extending stub shafts fixed to the boom and pivoted in said support plates so as to provide a generally horizontal axis for the boom, a cable drum journalled in said lower end of said boom on said horizontal axis, one of said stub shafts having a radial flange portion positioned outwardly of the support plate in which it is pivoted, and a motor assembly for driving said drum fixed to said flange portion and drivingly coupled to said drum.

2. The combination of claim 1 in which said stub shafts are annular and said drum is journalled in bearings set in the inner ends of the annular stub shafts so that the boom and drum rotate on the same axis.

3. The combination of claim i2 in which said motor assembly includes a mounting plate that is secured to said ange portion, the combination including a bearing set in said mounting plate concentric with said stub shafts,`

and a drive shaft for drivingly` coupling said drum and said motor assembly, said drive shaft passing through the center of said drum and having one end journalled by said mounting plate bearing and the other end secured to the drum.

HARVEY C. HORNSBY, Primary Examiner U.S. Cl.' X.R. 

